CTNI-68. EFFICACY OF TTFIELDS IN ELDERLY PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA (GBM) – SUB-GROUP ANALYSIS OF THE EF-14 TRIAL
Abstract BACKGROUND Tumor Treating Fields (TTFields) are an anti-mitotic, regional treatment that utilizes low intensity alternating electric fields delivered non-invasively to the tumor using a portable medical device. In the EF-14 phase 3 study leading to FDA approval, TTFields significantly extended survival in newly diagnosed GBM when added to maintenance temozolomide (TMZ). Elderly GBM patients usually have worse prognosis and often receive only partial treatment for the disease. This sub-group analysis examined the effects of TTFields in the elderly population (≥65 years of age) enrolled in the EF-14 study. METHODS All 134 elderly patients (≥65 years of age) from the EF-14’s intent-to-treat population were included in the analysis, Overall survival (OS) and progression-free survival (PFS), as well as adverse event frequency and severity were compared between the TMZ/TTFields arm and the TMZ alone arm. RESULTS The median age was 69 (range: 65–83), median KPS was 90%, and 69% were male. Median PFS from randomization was 6.5 months versus 3.9 months in the TMZ/TTFields versus TMZ alone arms, respectively (hazard ratio [HR], 0.47 [95%CI 0.30, 0.74] P< 0.0236). Median OS was 17.4 months versus 13.7 months in the TMZ/TTFields versus TMZ alone arm, respectively (HR 0.51 [CI 0.33, 0.77] P< 0.020). Serious adverse events (SAEs) were reported in 39% of patients treated with TMZ/TTFields and in 33% of patients treated with TMZ alone. None of the SAEs were considered related to TTFields but attributed to TMZ or to the underlying disease. Grades 1–2 skin AEs related to TTFields were observed in 51% of patients. CONCLUSION Consistent with the overall outcome of the EF-14 study, elderly patients treated with TMZ/TTFields showed significantly better OS compared to patients on TMZ alone, and without increase in grade III or IV toxicity.